Two subglacial lakes in the western part of Vatnajökull ice cap, southeastern Iceland, 10 and 15 km WNW of Grímsvötn volcano, are the source of regular jökulhlaups in the Skaftá river. The eastern cauldron featured a jökulhlaup that started on 30 September 2015.
The seismic signals generated by the flood were recorded using two seismic arrays (clusters of seismometers) operated by the Dublin Institute for Advanced Studies (DIAS) and the Icelandic Meteorological Office’s national seismic network, SIL. The arrays were maintained outside Vatnajökull ice cap. In the Vatnajökull region, the SIL network consists of stations that are partly installed on nunataks and within the ice.
We performed array-processing in the frequency domain (FK-analysis) on data filtered 1.2 to 2.6 Hz using the array-processing code as implemented in Obspy to derive back azimuth and slownesses of a tremor source propagating with the flood front. We perform beam stacking in the time domain on data filtered from 5 to 20 Hz to derive the back-azimuth of high-frequency transients moving with the flood front.
We used the SIL network for location and magnitude determination of 45 events near the cauldron and the flood path. These are possibly 22 icequakes and 23 earthquakes.
We used the array data to apply an STA/LTA filter and template matching approach on data filtered from 1 to 15 Hz to detect 669 events associated with the flood. 30% of these could be clustered into families and are likely due to the ice-shelf collapse once the subglacial lake drained.
These catalogs are further discussed and evaluated in Eibl et al. 2020 and Eibl et al. 2023. This data publications releases the catalogs of (i) tremor, (ii) located events and (iii) STA/LTA detected and clustered events.